Contrast and lighting enhancement

It was rather sketchy attempt of making the game look better.
I didn't use all posible options due to some FPS drops. I didn't use HDR for example.
Generally it's based on Ambient Light effect and few minor, and I recommend to tweak this effect individually.
Personally among 1.1 and 2.0, 1.0 is my favourite one, but it's sometimes too bright near more yellow areas. But I like it.